194 DR. S. H. LONG ON THE MOSQUITO-MALARIA THEORY. 
season, merely depending upon Mosquito protection as a preventative 
against the disease. The place chosen by them was near Ostia, on 
the mouth of the Tiber, “a water-logged, jungly spot teeming with 
insect life.” This part of the Campagna is so infested with the 
disease that all the labourers who go to reside there during the 
harvesting operations invariablj’' contract it, and hardly any one 
passes a night there during the malarial season who does not fall 
a victim to the effects of the poison. These two men took with 
them a wooden hut, constructed in England, and in this they dwelt. 
The doors and windows of the hut, and every other possible source 
of entry for Mosquitoes were carefully guarded with wire Mosquito 
curtains. They did not take a grain of quinine with them. During 
their stay there they were always careful to be in their hut one 
hour before sunset, and not to leave it again until one hour after 
sunrise ; the rest of the day they spent outside, ever having an eye 
for Anopheles. Both these men have since returned to England, 
and neither has developed Malaria, as they assuredly would have 
done long before now had they been infected. 
Having proved to you, as I hope, that there is now no longer 
a shadow of a doubt but that the Mosquito acts as a carrier of the 
Malaria infection, we will now briefly review what is known of the 
Structure , Life- History, and Habits of these very interesting little 
insects. 
I must tell you first of all that only Mosquitoes of a certain 
genus, the Anopheles, have so far been shown to serve as hosts of 
the malarial parasite, and of the forty-two species of the Anopheles 
at present identified, eight (and possibly more) are capable of doing 
this. "There are three species known in England : Anopheles 
maculipennis (vel. A. claviyer), Anopheles bifurcatus, and Anopheles 
nigripes. Of these three, the Anopheles maculipennis is by far the 
most common, and is the most widespread over the continent of 
Europe. The species with which these are most likely to be con- 
founded are the Culicidae, and as it is a rule that only the female 
sucks blood, it is important to be able to differentiate the female 
Culex from the female Anopheles, for the evidence of a considerable 
amount of experimental work entirely exculpates Mosquitoes of the 
genus Culex from any part in the transmission of human malarial 
fever. The two diagrams I now show you will serve to make this 
difference evident. 
